Many individuals in health care facilities are able to achieve sufficient caloric intake through eating prepared meals. However, a sizable number of such patients are unable to ingest enough food to meet their body's needs. Examples of these individuals would include burn patients, whose daily caloric needs are often in excess of 5,000 calories, and critically ill, weak, or comatose patients who may be unable to chew their food. For these patients, caloric supplementation through parenteral, also known as intravenous, feeding is not a viable alternative.
In response to this problem, liquid foods have been developed for enteral feeding. Enteral feeding is providing nourishment through the oral tract by defined nutritional diets. Typically, enteral feeding utilizes a nasogastric tube to transport the liquid nutritional products from the container through the patient's nasal cavity and thence into the stomach. Early enteral nutritional product containers were empty, sterilized pouches which were filled with sterilized, canned product at the point of use. The filled pouch was spiked by a cannula. However, there are shortcomings associated with that type of packaging including potential product contamination and extensive set-up-time. In response to that problem, a multi-layer plastic bottle was developed having a central layer which provided an oxygen barrier, therefore permitting the bottle to be pre-filled with food product which provided greater shelf-life and less spoilage. This type of plastic bottle utilizes an attached membrane which must be pierced so as to permit the commencement of the feeding process.
Ported closures are well known, an example of which is Steidley, U.S. Pat. No. 4,022,258 which discloses a closure for surgical irrigation fluid containers as opposed to one for enteral nutritional product containers. Steidley discloses a large spike member which can pierce a plastic cap with the spike member including a conventional filter positioned adjacent the external surface of the cap. However, Steidley does not address the unique problems associated with the physical composition of enteral nutritional products. Enteral nutritional products are dissimilar from fluids introduced by intravenous feeding primarily due to the presence of minerals and other solids which tend to form a sediment which settles to the bottom of the inverted container during feeding. Additionally, entera1 nutritional products are extremely viscous.
Current enteral nutritional product containers utilize one-piece injection molded, relatively rigid plastic threaded caps. The caps are often pre-attached to the plastic tubing of a delivery set, thus not permitting the use of "spike"-type feeding sets. Even in the cases of caps designed for use with "spike"-type feeding sets, there are three major drawbacks. First, due to the desirability of obtaining a leakproof seal, significant torque must be applied to the threaded portion of the cap, however this requires the cap to be fabricated from a relatively rigid plastic which may prove difficult for nurses to easily cannulate. Second, conventional closures for enteral nutritional containers utilize a gasket which is maintained in position by a centrally located annular ring which depends downwardly from the bottom surface of the cap. However, in shipping, the annular ring may either accidentally puncture the membrane if sufficient downward pressure is applied to the cap, or the ring may downwardly deform the membrane enough such that after cannulation has occurred, air may inadvertently find its way into the nasogastric tube resulting in aspiration of the patient. Third, even if the above drawbacks are overcome, if the diameter of the cannula is too wide to pierce the cap's membrane or too narrow to remain engaged with the container, "spike"-type feeding must be abandoned or a completely new one-piece cap must be obtained that can accommodate the diameter of the cannula. Existing one-piece closures cannot overcome the above disadvantages.
It is thus apparent that the need exists for an improved closure for pre-filled enteral nutritional product containers which ensures a leakproof seal as well as easy cannulation, while at the same time overcoming the drawbacks associated with existing one-piece closures.